A legume is a crop that is within the Fabaceae family. In agricultural terms, they are known for their ability to fix atmospheric nitrogen and provide a high-protein feed source for livestock. The Farming for a Better Climate Soil Regenerative Agriculture Group have been trialling ways to introduce legumes into their arable rotations.
In Scotland, the most common legume on farms is white clover which is often mixed with grass to reduce the reliance on fertiliser and increase the protein content of grazing and silage. However, in an arable setting, field beans, spring peas, red clover or lupins are often found within the rotation.
Legumes can bring many benefits including species diversification; a new income stream; a more manageable workload; reduced fertiliser use on subsequent crops; low production costs; a break for cereals and the early sowing of the next crop in some situations.
However, there are also some common challenges to growing legumes, including weed, pest and disease management. Peas, beans, and clover are all susceptible to Sclerotinia and too many susceptible crops within a rotation can cause a high disease burden.
Avoiding crops such as carrots, oilseed rape, potatoes, and legumes all in close succession can counter some of this burden. Beans are also susceptible to chocolate spot; however, this can usually be controlled with a fungicide such as metconazole. Beans can also be vulnerable to black bean aphid which may require an insecticide treatment to be used.
Over the past two years the Soil Regenerative group have overcome many of these problems and have found that both peas and beans provide valuable breaks within a rotation which is dominated by cereals. Hugh Black at Backboath grew both spring and winter beans in 2021, with the crops yielding 4.6t/ha and 5.68t/ha respectively. Hugh harvested his winter beans in the middle of September, with the spring beans approximately two weeks later at the end of September. Beans leave the soil in good condition for the following crop, the soil is very friable, making establishing wheat after beans much easier.
Read more:
- Bees will benefit from better management of legumes
- Europe looks to increase crop rotations with beans and peas
- Arable Matters: Quickening the pulse of an old has-bean
Different legumes provide different challenges and benefits on farm – the table below highlights some of the pros and cons of the most common legumes on Scottish farms:
Including legumes in an arable rotation can have many benefits, and deciding which legume is right for your business will depend on several factors, including desired end market for the pulse, availability of equipment and land suitability.
Peas can be grown for vining, where fields are usually let out, or for combining where they can be used as a high-protein feed source. Red clover is often made into a high-protein silage which may be more suited to a mixed farming situation. Alternatively, lupins can be grown as an alternative to spring barley if a wet autumn results in a reduced wheat area being established.
To find out more about the work of the Soil Regenerative Agriculture Group and climate-friendly ideas for your farm, visit www.farmingforabetterclimate.org
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